# Chapter 2b - Built-in Functions

## Animation

## Built in Functionsโ

### Using + with strings.โ

we know that when we use `+`

with numbers, the program will give us the mathematic operation of the sum of the numbers. But what happens when we have words?

`s1 = "Agent" # assign values to string 1 and string 2`

s2 = "007"

print ("Using + with strings ")

print("String 1: " + s1) # print values of s1 and s2

print("String 2: " + s2)

print ("String 1 + String 2: " + s1 + s2) # concatenation of strings - Line 18

print("")

## ๐งช Try the code out!

### str(), min(), max()โ

`# Part 1`

a = 12 # assign value to variable a

b = 3 # assign value to variable b

c = 4 # assign value to variable c

print ("a: " + str(a) + " b: " + str(b) + " c: " + str(c) ) # print values for a, b and c

print ("Minimum of a, b and c is " + str(min(a,b,c) ) ) # print minimum value among a, b and c # Line 8

print ("Maximum of a, b and c is "+ str(max(a, b, c) ) ) # print maximum value among a, b and c # Line 9

print("") # print an empty line

print("")

## ๐งช Try the code out!

### int() Converting Words into Integersโ

`# Part 3`

a = 12 # assign value to variable a

s2 = "007"

print ("A string which holds a number can be changed to number data type like this:")

s2_as_a_num = int(s2) # typecasting a number into a string

print("sum of a and s2_as_a_num: " + str(s2_as_a_num + a)) # adding a typecasted number with another

## ๐งช Try the code out!

### pow() and abs()โ

`a = 8`

b = 2

c = -9

d = 9.9

print(pow(a,b)) # returns a raised to the power b

print(pow(d,0)) # returns d raised to the power of 0

print(abs(c)) # returns the absolute value of c

print(abs(d)) # returns the absolute value of d

## ๐งช Try the code out!

### Exerciseโ

##### Exercise: Counting Apples

write a program that tracks the mumber of apples the user ends up with after starting with a set number of apples. Students can set the initial number of apples to a number of their choice. The output should follow this script:

`You have ___ apples.`

You plant one tree from a seed you found in your attic and harvest five apples from it. You now have ___ apples.

You extract seeds from every apple you have, discard the apples, and plant all the seeds. You harvest four times as many apples as you had. You now have ___ apples.

You look over your apples and realize some of the trees were diseased! You have to throw out half of your apples. You now have ___ apples.

You decide to bake an apple pie. This requires six apples. You now have ___ apples.

Example Output

`You have 20 apples.`

You plant one tree from a seed you found in your attic and harvest five apples from it. You now have 25 apples.

You extract seeds from every apple you have, discard the apples, and plant all the seeds. You harvest four times as many apples as you had. You now have 100 apples.

You look over your apples and realize some of the trees were diseased! You have to throw out half of your apples. You now have 50.0 apples.

You decide to bake an apple pie. This requires six apples. You now have 44.0 apples.